Thank you very much for the IPCC file. I've been trying to get MMS working on and off ever since 3.0 came out (using the SIM in a different AT&T phone, calling AT&T to tell them 'MMS isn't working on my non-iPhone', etc.)
This file and guide work perfectly. I installed the IPCC file, rebooted my phone and everything works fantastic.
Also, my phone is jailbroken with the 3.1 firmware (using the pwnage tool that was released yesterday) so all of you guys with JB phones can rest with ease, it works fine. My VVM wasn't working after the JB, and it doesn't seem to be working now either, so I don't know what broke it.
iPhone 3G (not S)
Thanks again!
Edit: I have Family Messaging Unlimited